Lesson 2: The Compressor (Archives & Backups)

Servers generate mountains of data — logs, configs, databases. You need to compress, archive, and transfer these efficiently. Master the art of squeezing files and you'll save bandwidth, storage, and time.

tar — The Tape Archiver

tar bundles multiple files into a single archive. Combined with compression, it's the standard backup tool.

Creating Archives:

tar -czf archive.tar.gz folder/     # Create compressed archive
tar -cf archive.tar folder/         # Create without compression

Reading Archives:

tar -tzf archive.tar.gz             # List contents without extracting

Extracting Archives:

tar -xzf archive.tar.gz             # Extract to current directory
tar -xzf archive.tar.gz -C /tmp/    # Extract to a specific directory

Decoding the Flags

| Flag | Meaning | |------|---------| | -c | Create a new archive | | -x | Extract files from archive | | -t | List contents of archive | | -z | Use gzip compression | | -f | Specify the filename | | -v | Verbose (show progress) |

Other Compression Tools

| Tool | Extension | Best For | |------|-----------|----------| | gzip | .gz | Fast compression, standard Linux | | bzip2 | .bz2 | Better compression, slower | | zip/unzip | .zip | Cross-platform compatibility | | xz | .xz | Best compression ratio |

gzip large_log.txt              # Compresses → large_log.txt.gz
gunzip large_log.txt.gz         # Decompresses back
zip backup.zip file1 file2      # Create zip archive
unzip backup.zip                # Extract zip

Backup Strategy

A simple daily backup script:

#!/bin/bash
DATE=$(date +%Y-%m-%d)
tar -czf "/backups/server-$DATE.tar.gz" /etc /var/log /home
echo "Backup created: server-$DATE.tar.gz"

Mission Objective

Practice archiving and restoring data:

1. Pack it up: Create a compressed archive with tar -czf backup.tar.gz /etc/hostname /etc/os-release.
2. Inspect it: List the archive contents with tar -tzf backup.tar.gz.
3. Unpack it: Extract the archive with tar -xzf backup.tar.gz.

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Pro Tip

Combine your backup script with a cron job (from the previous module) to create automatic nightly backups. Add find /backups -mtime +30 -delete to clean up archives older than 30 days!